Implement stabilization method and apparatus

ABSTRACT

The fluid pressure supplied to the hydraulic cylinders which extend the stabilizing arms of a backhoe is replenished by pressure from the bucket-controlling cylinder whenever the armextending pressure falls below the bucket-controlling pressure, to offset the leak-down which eventually causes the arms to lose their original position.

United States Patent King Aug. 26, 1975 [54] IMPLEMENT STABILIZATIONMETHOD 3,583,585 6/1971 Joyce 214/762 AND APPARATUS 3,653,523 4/1972bong 3,680,714 8/1972 Holmes 212/145 [75] Inventor: Donald R. King,Terre Haute, Ind. [73] Assigne z .1. 1. Case Company, Racine, Wis.Primary ExaminerRobert J. Spar Assistant ExaminerRoss Weaver [22] Flled'July 1973 Attorney, Agent, or Firm-Cullen, Settle, Sloman & [21] Appl.No.: 378,359 Cantor [52] US. Cl 214/138 R; 60/484; 91/412; [57] ABSTRACT5 I Cl 212/ The fluid pressure supplied to the hydraulic cylinders l 62which extend the stabilizing arms of a backhoe is re- [58] of earch 6 64 plenished by pressure from the bucket-controlling cylinder wheneverthe arm-extending pressure falls below R f the bucket-controllingpressure, to offset the leak- [56] e erences Clted down which eventuallycauses the arms to lose their UNITED STATES PATENTS Original position2,890,805 6/1959 Pilch 214/762 3,563,137 2 1971 Grabcr 214/763 2 Clams,3 Drfiwlng Flgllres PATENTEU Auczslrs SHEET 1 OF 2 tmmma HmxuDm EOOmIMPLEMENT STABILIZATION METHOD AND APPARATUS BACKGROUND OF INVENTION Thepresent invention relates to stabilizing arrangements for vehicles,particularly for mobile machinery such as vehicle-mounted backhoes,cranes, shovels, or the like.

It is conventional to mount a variety of mobile machinery on atractor-like vehicle, such machinery often including a mounting frame towhich is pivoted a swingframe or boom capable of swinging laterallyabout a vertical axis relative to the mounting frame of the vehicle.Material handling or holding means, such as buckets or other implements,are usually carried by the boom for movement therewith.

Generally, the wheelbase of the ground-engaging wheels of the tractor isinsufficient to provide adequate stability for the machine during theoperation of the swinging implement. This is particularly true inearthmoving machinery, such as shovels or backhoes, which are adapted topick up a heavy load in an extended position of the boom and to raisethe load and swing it, often to the opposite side of the tractor. Thisswinging movement of the heavily loaded and extended boom tends tounbalance the tractor, with the resulting danger of tipping ifsupplementary stabilizing means are not provided.

One well known form of stabilizing means are the Outriggers orstabilizing arms adapted to be extended laterally from each side of thevehicle. An example of these stabilizing arms is shown in U.S. Pat. No.3,630,544 to Grisham, et al, entitled Stabilizer for Earth MovingMachinery. The arms are caused to extend downwardly or retract upwardlyabout horizontal axes by hydraulic cylinders pivotally mounted to thevehicle frame. During operation of the backhoe, the stabilizing arms arenormally maintained in their extended position by constant hydraulicpressure.

A common problem in the use of these hydraulically operated stabilizingarms is hydraulic leakage past the cylinder piston seal or past thevalve spool land. This constant leaking down of pressure prevents thecylinders from maintaining the preselected position of the stabilizingarms, and therefore requires the operator to interrupt his work toreadjust or reposition the stabilizing arms. In the past, one method ofminimizing this leakage has been to employ expensive pilot-operatedcheck valves. However, the expense of these valves makes them anunsatisfactory solution.

Accordingly, it is the principal object of this invention to provide animproved means for preventing leakdown of hydraulic pressure in thehydraulic cylinders which control the position of the stabilizing armsof a piece of earth-moving equipment.

SUMMARY OF INVENTION The present invention involves the provision ofauxiliary conduits interconnecting the supply conduits for theimplement-positioning cylinder with the armextending chambers of thestabilizing arm-positioning cylinders. These auxiliary conduits areprovided with check valves which permit fluid flow only toward thestabilizing arm controlling cylinders. Thus, any leakage of fluid fromthe stabilizing cylinders will be replenished by fluid from theimplement-positioning cylinder whenever the fluid pressure in thestabilizing cylinders falls below that in the implement-positioningcylinder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of atractor vehicle having a conventional backhoe attached thereto, andprovided with stabilizing arms.

FIG. 2 is a schematic diagram of the hydraulic cylinders and associatedhydraulic control circuitry for the backhoe and stabilizing arms.

FIG. 3 is an enlarged view of a check valve forming a portion of thecircuitry of FIG. 2.

DETAILED DESCRIPTION OF THE DISCLOSURE Referring to FIG. 1, there isillustrated a tractor 10 having a conventional backhoe l2 pivotallymounted on a supporting frame 14 secured to the rear of the tractor. Acontrol panel 16 controls the operation of the backhoe as well as thatof the stabilizing arms 18 extending laterally from each side of tractorl0.

Backhoe 12 includes a bucket 20 pivotally mounted on the outer end ofdipper arm 22, which is in turn pivotally mounted on boom 24 pivotallyconnected to supporting frame 14. Movement of bucket 20 relative todipper arm 22 is controlled by bucket hydraulic cylinder 26, whilemovement of dipper arm 22 relative to boom 24 is controlled by dipperhydraulic cylinder 28. Boom 24 can be lifted or lowered under thecontrol of boom hydraulic cylinder 30, while lateral swinging movementof boom 24 is effected by swing hydraulic cylinders 32.

As is conventional, each of the stabilizing arms 18 may be pivotallylowered into their extended groundcontacting positions, as illustrated,or raised to their retracted positions by hydraulic cylinders 34, 36.

As shown in FIG. 2, the various hydraulic cylinders disclosed herein aretypically of the double-acting type. The circuitry includes a controlvalve, schematically shown at 38, which includes a series of manuallyoperable valves for controlling each of the hydraulic cylindersassociated with the stabilizing arms and backhoe. These valvesdistribute the fluid pressure supplied by pump 40 to the appropriatechambers of the desired cylinders. Supply lines 42 and 44 carry fluid tothe armextending chambers of cylinders 34 and 36, while lines 46 and 48carry fluid to the retracting chambers of those two cylinders.Similarly, lines 50 and 52 carry fluid to the respective chambers ofbucket cylinder 26. The circuitry and elements described thusfar areconventional. For the sake of simplicity, hydraulic cylinders 28, 30 and32, along with their supply lines, have been omitted from FIG. 2, sincethey are not essential to the operation of the present invention.

According to the present invention, a fluid distribution tap 54 isprovided in line 50 leading to bucket cylinder 26. As will be seen fromFIGS. 1 and 2, line 50 is pressurized whenever the cylinder rod ofcylinder 26 is to be extended, as would be the case when the bucket ispositioned to lift dirt. Auxiliary supply lines 56 and 58 lead from tapfitting 54 to the respective stabilizing arm extending chamber supplylines 42 and 44, joining with the supply lines at Tee fittings 60 and62, respec tively. Check valves 64 and 66 are provided in lines 56 and58, for a purpose to be described below.

As shown in FIG. 3, check valves 66, which is typical of theconstruction of check valve 64 as well, includes an orifice 68 which iscontrolled by a ball type valve element 70. A pair of spring washers 72within the check valve function to keep the ball from blocking flow atthe right end of the valve. As is conventional, the ball will seat inorifice 68 whenever there is a tendency for fluid to flow from right toleft in FIG. 3, but will permit free flow of fluid from left to right.

Stabilizing arms 18 are extended to their operative position asillustrated in FIG. 1 whenever fluid pressure is supplied through lines42 and 44. In the event that some leakage from cylinders 34 and 36 orfrom control valve 38 occurs, replenishing pressure will be supplied tolines 42 and 44 from line 50 which supplies the bucket controllingcylinder 26. Thus, as shown in FIG. 2, replenishing fluid will besupplied through tap connection 54, line 56, check valve 64 and Tee 60,or through line 58, check valve 66 and Tee 62, whenever the pressure inline 50 exceeds that in either line 42 or 44.

The source of the replenishing fluid pressure has been described asbeing supply line 50 for the rodextending chamber of bucket-controllingcylinder 26. This is the preferred embodiment of the present invention,because it has been discovered that this chamber normally has thehighest fluid pressure of any of the backhoe-controlling cylinders, andtherefore is most likely to have the necessary higher pressure to serveas a replenishing source for the stabilizing arm cylinders. However, itis to be understood that the supply lines (not illustrated) for thedipper cylinder 28 or boom cylinder 30 might alternatively be employedas replenishing sources if such lines had the necessary higher pressureat times when replenishment might be required.

This invention may be further developed within the scope of thefollowing claims. Accordingly, the above specification is to beinterpreted as illustrative of only a single operative embodiment ofthis invention, rather than in a strictly limited sense.

I now claim:

1. In a land vehicle having a vehicle mounted extensible tool controlledby a double acting pressure cylinder having tool extending andretracting chambers and a pair of vehicle-stabilizing, ground-engagingarms, said arms each having a double acting fluid pressure cylinderincluding arm extending and retracting chambers and said arms extensibleby said cylinders to support and stabilize said vehicle during extensionand movement of said tool, and said cylinder chambers each selectivelysupplied with fluid pressure by a pump through a system of conduits, theimproved control circuit for replenishing any loss of fluid pressure ineither of said arm extending cylinder chambers, comprising:

fluid supplementing circuits interconnecting each of said cylinder armextending chambers with the sup ply conduit of said cylinder toolextending chamber, and

a check valve in each of said fluid supplementing circuits permittingfree flow of fluid from said tool supply conduit of said tool extendingchamber to said cylinder arm extending chambers when the fluid pressurein said tool supply conduit exceeds the fluid pressure in either of saidcylinder arm extending chambers, maintaining said arms in supporting andstabilizing position and said check valves preventing fluid flow fromsaid cylinder arm extending chambers to said tool supply conduit of saidcylinder tool extending chamber.

2. The fluid supplementing circuit defined in claim 1, characterized inthat said tool is a backhoe-mounted bucket, and wherein said fluidsupplementing circuits interconnect the rod-extending chamber supplyline for the bucket with the stabilizing arm-extending chamber supplyline.

1. In a land vehicle having a vehicle mounted extensible tool controlledby a double acting pressure cylinder having tool extending andretracting chambers and a pair of vehiclestabilizing, ground-engagingarms, said arms each having a double acting fluid pressure cylinderincluding arm extending and retracting chambers and said arms extensibleby said cylinders to support and stabilize said vehicle during extensionand movement of said tool, and said cylinder chambers each selectivelysupplied with fluid pressure by a pump through a system of conduits, theimproved control circuit for replenishing any loss of fluid pressure ineither of said arm extending cylinder chambers, comprising: fluidsupplementing circuits interconnecting each of said cylinder armextending chambers with the supply conduit of said cylinder toolextending chamber, and a check valve in each of said fluid supplementingcircuits permitting free flow of fluid from said tool supply conduit ofsaid tool extending chamber to said cylinder arm extending chambers whenthe fluid pressure in said tool supply conduit exceeds the fluidpressure in either of said cylinder arm extending chambers, maintainingsaid arms in supporting and stabilizing position and said check valvespreventing fluid flow from said cylinder arm extending chambers to saidtool supply conduit of said cylinder tool extending chamber.
 2. Thefluid supplementing circuit defined in claim 1, characterized in thatsaid tool is a backhoe-mounted bucket, and wherein said fluidsupplementing circuits interconnect the rod-extending chamber supplyline for the bucket with the stabilizing arm-extending chamber supplyline.